Apparatus for centrifuging electrically conducting liquids



Feb. 11, 1969 M. w. ROBERTS ETAL 3,426,967

' APPARATUS FOR CENTRIFUGING ELECTRICALLY CONDUCTING LIQUIDS Filed Dec. 23, 1965 United States Patent Office 3,426,967 Patented Feb. 11, 1969 2 Claims ABSTRACT OF THE DISCLOSURE An apparatus centrifuges an electrically conducting liquid confined in an annular cylindrical channel. A magnetic field is applied in the direction of the axis of the channel through the liquid. An electric current is forced to flow radially through the liquid in the channel perpendicular to the magnetic field to cause a rotational motion of the liquid in the channel.

The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.

This invention relates to centrifuges, and more particularly to apparatus for centrifuging an electrically conducting liquid.

An object of the present invention is to provide novel apparatus for centrifuging an electrically conducting liquid.

A further object of the invention is to provide apparatus for continuously centrifuging an electrically conducting liquid without any moving or rotating parts in the apparatus except the liquid itself.

A still further object of the present invention is to provide apparatus capable of controlling the angular velocity of an electrically conducting liquid being centrifuged wherein no moving parts are used in the ap paratus.

Briefly, the above objects are accomplished by containing the electrically conducting liquid to be centrifuged in an annular, cylindrical channel or conduit and applying a magnetic field traversing the fluid in the direction of the axis of the cylinder forming the channel. An electrical current is then formed to flow radially in the channel and perpendicular to the established magnetic field, thereby inducing a force in the liquid normal to the directions of current flow and magnetic flux and causing rotational motion of the liquid within the cylindrical channel. The angular velocity of the liquid is, of course, proportional to the strength of the impressed electric and magnetic fields.

A better understanding of the nature and further objects of the invention will be obtained from the following detailed disclosure accompanied by the single drawing which is a partially sectioned schematic of apparatus according to the present invention.

Referring to the drawing, a centrifuge 10 is located between a north magnetic pole 12 and a south magnetic pole 14. The centrifuge 10 is supported on ahorizontal circular base 16. A cylindrical insulating layer 18 covers the entire base 1'6, thereby electrically isolating the rest of the centrifuge 10 from the base 16. A cylindrical metal wall 20 rests on the insulator 18 and forms the outer containing wall for the liquid to be centrifuged. The wall 20 also serves as an electrode, as explained below.

A second metallic electrode 22 in the form of a cylinder is located inside of and coaxially with the outer wall 20, and it also rests on the insulator 18. The annular, cylindrical channel formed between the outer Wall 20 and electrode 22 is the passage in which an electrically conducting liquid 2'3 is confined while being centrifuged.

The upper portion of the electrode 22 is reduced to form a neck 22a of smaller diameter than the lower portion of electrode 22 and a horizontal, annular shoulder 22c is formed between the external surfaces of the lower portion of electrode 22 and the neck 22a. A conduit 22b extends through electrode 22 to allow for the entrance of the electrically conducting liquid 23 into the channel between outer wall 20 and electrode 22. The conduit 2% has an upper'extension which is formed radially inwardly to the center of the neck 22a of electrode 22. The conduit 22b then runs axially down and almost to the bottom of electrode 22. It there branches into four radial outlets into the channel formed between the outer wall 20 and electrode 22.

A cylindrical cover 24 fits around the upper reduced portion of electrode 22 and extends to and rests on the outer wall 20, being isolated therefrom by an insulating ring 25. There is a clearance between the bottom of cover 24 and the shoulder 220 of electrode 22 to allow for flow in recovering the supernatant liquid, as described below. Cover 24 has a depressed hollow 34 extending axially up to a point below the radial upper extension of conduit 22b in the neck 22a of electrode 22. The cover 24 has a first radial conduit 26 bored through it which is adapted to connect an inlet pipe 28 to the radial upper extension of the conduit 22b. The cover 24 has a second radial conduit 30 adapted to connect an outlet pipe 32 for the supernatant liquid to the hollow 34. The supernatant liquid, then, is recovered by passing over the shoulder 22c of electrode 22, filling the hollow 34 in cover 24, and flowing through the conduit 30 in cover 24 to the outlet pipe 3'2.

A second outlet pipe 38 to which is connected a valve 39 is shown in the drawing as being connected to the lower portion of the outer Wall 20. The pipe '38 is an optional feature of the device and would normally be used if the operation of centrifuging were going on continuously. The pipe 38 allows for the passage of slurry (that is, the centrifuged portion of the liquid containing a higher concentration of particulate matter) from the liquid 23.

A variable DC power source 35 has its output terminals connected between the neck 22a and the outer wall 20.

In the operation of the device, an electrically conducting liquid 23 from a source not shown is fed in through inlet pipe 28, through the conduit 26 of the cover 24, into the conduit 22b located in electrode 22 and into the channel formed between electrode 22 and outer wall 20. When electrical continuity is established between electrode 22 and outer Wall 20 via the liquid 23, a current fiows radially through liquid 23 from electrode 22 to outer wall 20 for the polarity of the DC power source 35 as shown in the drawing. With a magnetic field established from magnet 12 to magnet 14 (that is along the axis of the cylindrical channel formed by electrode 22 and outer wall 20) a counterclockwise (when viewed from the top) rotational motion will result from the force induced on the current-carrying liquid 23, according to the well known Flemings left hand rule for motors. The supernatant liquid isthen removed as described above through channel 30 in cover 24 to the liquid outlet pipe 32 in the direction of the arrow. The slurry is removed through outlet pipe 38, that is, when this feature is incorporated in the apparatus. It is noted that the electrode 22 and the outer wall 20, which also acts an an electrode, must be made of or plated with a material which does not dissolve 'an'odically in the liquid 23 being centrifuged.

The rotation force on the liquid 23 is proportional to the current density and the strength of the applied magnetic field is the liquid 23. Therefore, the angular velocity of the liquid 23, and consequently the centrifugal force applied to separate any particulate matter that may be in the liquid 23 may be varied by a simple adjustment of the variable DC power source 35.

It will be apparent that the invention may also be used to separate two immiscible liquids of different densities from each other if the major component is electrically conducting.

Since the embodiment described above is susceptible of various modifications and alternative constructions, it is to be understood that applicants do not intend to limit the invention to the specific form disclosed, but intend to cover all modifications and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for centrifuging an electrically conducting liquid, comprising:

(1) means defining a closed annular channel for containing electrically conducting liquid, said channel including an inner and an outer conducting wall coaxially positioned with respect to each other;

(2) means for electrically isolating said inner channel wall from said outer channel wall;

'(3) inlet means for injecting an electrically conducting liquid into said channel to establish electrical continuity between said inner and said outer channel wall;

(4) first outlet means located near the periphery of said annular chamber for removing high density constituents of said liquid;

(5) second outlet means located near said inner wall for removing lower density constituents of said liquid;

(6) means including a variable DC current source connected across said inner and outer channel walls for forcing a current to flow radially therebetween; and

(7) means for impressing a magnetic field in said conducting fluid in a direction parallel to the axis of said annular channel;

said magnetic field and said current cooperating to rotate said liquid in said annular channel.

-2. The apparatus of claim 1 in which said inner channel wall comprises a fixed conducting electrode having a hollow central portion serving as a part of said inlet means and permitting continuous influx of liquid to be centrifuged into said annular channel.

References Cited UNITED STATES PATENTS 9/1953 Crever 1031 5/1961 Cochran, et al. 103-l HENRY T. KL'INKSIEK, Primary Examiner. 

